Method of and means for reproducing and amplifying weak pulsating



L. DE FOREST METHOD OF AND MEANS FOR aevaooucma AND AMPLIFYING WEAK PULSATING CURRENTS. APPLICATION FILED SEPT. 8. 1914.

1L3 14,250. Patented Aug. 26, 1919;

lllllmlh s" PATENT ores.

LEE DE FOREST, or NEW YORK, N. Y., Assrenon, BY MESNE ASSIGNMENTS, 'ro DE FOREST RADIO TELEPHONE AND TELEGRAPH DELAWARE.

COMPANY, A CORPORATION OF METHOD OF S FOR REPRODUCING AND AMPLIFYING- WEAK PULSATING CURRENTS.

Specification of Letters Patent.

Patented Aug. 26, 1919.

' Original application filed June 24, 1913. Serial No. 775,529. Divided and this application filed September 8,

' 1914, Serial No. 860,713.

tion in Methods and Means for Reproducing and Amplifying Weak Pulsating Currents, of which the following is a specification.

This invention relates to methods of and means for reproducing and amplifying weak pulsating currents, and embodies subject matter divided from my prior application Serial No. 77 5,529, filed June 24, 1913.

The object. of the invention is to provide means which are simple and efficient for reproducing and amplifying weak pulsating currents for use in connection with electroresponsive devices, such as sound emitting means, etc.

A further object of the invention is to provide a method and means of-the character referred to whereby weak pulsating currents are reproduced and amplified at a plurality of points or stations.

A further object of the invention is to provide means whereby any desired degree of amplification is secured by means of a plurality of amplifiers wherein a common circuit is employed to supply current to the plurality of amplifiers.

Other-objects of the invention will appear more fully hereinafter.

My invention consists substantially in the construction, location, relative arrangement of parts, and method of operation, all as will be more fully hereinafter set forth,as shown in the accompanying drawing, and finally pointed out in the appended claims.

vReferring to the drawing: Figure 1 shows means for reproducing and amplifying weak pulsating currents at a terminal of the filament 4 of the master 95 plurality of locations from a single source.

Fig. 2 shows another arrangement for accomplishing the objects and purposes of my invention.

In accordance with the principles of my invention I propose to employ weak pulsating currents from any suitable source and to amplify the same and utilize the amplified current for any desired purpose such as for the production of sound waves or for other purposes, and, in a somewhat more limited statement, to utilize the weak pulsating currents, in the manner and for the purposes stated, from a single source at'a plurality of different points or locations,

after amplifying the same.

My invention may be carried out in many different ways, and in the accompanying 60 drawings I have shown two arrangements of operation and practical apparatus for the a purpose.

. Generally speaking, I employ one or more master amplifiers in the form of an audion,

or audions, which initially receive the weak pulsating currents and amplifies them, and one or more auxiliary or secondary amplifiers in the form of audions which serve to increase the amplification of the currents and deliver the same to one or moredifi'erent locations or points and to electro-responsive devices for practical utilization.

The amplifiers, master and auxiliary, are arranged in suitable circuit arrangement with respect to each other to enable them to accomplish their respective functions.

Referring to Fig. 1, reference numeral 1 designates schematically a source of weak pulsating current which-is electrically connected to a masteraudion 2, by means of the transformer 3. The filament 4, of the master audion, is supplied with current from a suitable source, such as a battery shown at 5- The grid 6 of the-same audion. is connected to one terminal of the transformer 3, and the plate or wing 7 of the same audion is connected in circuit with a suitable source of current shown at 8, and

in series with the primaries 9, 10, '11, etc., of the various transformers included in the separate circuits of the auxiliary or secondary audions, and the circuit contlnues to a audion, which terminal is also connected to the other terminal of the secondary of transformer 3. The secondaries. 12, 13, 14, etc., of the series of transformers are shown respectively connected to thegrids 15, and 109 current from a source shown -at 20, such i as a battery. I prefer to interpose reactance prefer to use transformer 3 as a step-up transformer to raise thev'oltage of the weak pulsating current derived at 1. The trans- "formers 912 1013, 11--14, etc., may be of any suitable type, but I prefer to use one-to-one two coil transformers. actances' or choke coils 21 may be either of the adjustable type or of the fixed type, having a predetermined reactance. The electro-responsive devices indicated at 24 may be of. any desired construction or character, and it is evident that theymay be placed at points remote from one another I as may be desired.

The operation of the arrangement described is apparently simple. The weak pulsating currents derived at source 1 are transmitted through the transformer 3 to the master audion 2 which amplifies-the current and transmits the same by means of transformers 9-12, 1013, 1ll4, etc., to the auxiliary or secondary audions. Each of the auxiliary audions amplifies the current received thereby, and transmits the same to the electro-responsive devices 24 to be utilized as may be desired as hereinbefore described.

In Fig. 2 I have shown ,an arrangement wherein an audion is employed to act in the capacity of a-step-up transformer between the source of weak pulsating currents and.

' the master audion, and aplurality of auxil iary audions are employed associated with the master audlon, and in parallel relation to each other, so that each auxiliary audion -48 which completes the circuit of the fila may control the action of a lurality of;

electro-responsive devices. In t is arrangement the filaments of all ofthe audions employed are supplied with current' from a common source. The weak pulsating currents are derived from any suitable source schematically shown at 1, which is electrically connected to audion 26 by means of the transformer 25. This transformer may be of any desired type, butI find it preferable to use a one-to-two step-up transformer, one

endof the secondary of which is connected to the grid of audion 26, and the other end is connected to a terminal of the filament of said audion, which terminal is also con nected to common source. 47 and to. the source 28. The other terminal of said filament is connected to the variable resistance The rep mentto the source 47. The plate or wing of the audion 26 is connected to one side of the the common source 47, and the other terminal is connected to the variable resistance 49, which completes the circuit of the filament to the common source 47. The plate or wing element of the master audion is connected to the primary of the transformer 33. This transformer may be of any suitable type,

; but I find it preferable to use a one-to-one two coil transformer. The wing of the mas-. ter audion 27 is also connected to an open circuited gap indicated at'35. One side of the secondary of transformer 33 is open-circuited at 37, and the other side is connected to the grid of auxiliary audion 31. When more than one auxiliary audion is employed,

the plate element of master audion 27 is connected to one side of a circuit including the primaries of as many transformers as there are auxiliary audions, said primaries being connected in series, and the other sideof the circuit being open-circuited. I have shown, for illustrative purposes, two auxiliary audions 31, 32, said auxiliary audions being in parallel relation toeachother and electrically connected to the master audion 27 by means of the transformers 33, and 34. The grids of the auxiliary audions are connected to one side of thesecondaries of the respective-transformers associated therewith, the other side being open-circuited. The filaments of the auxiliary audions are connected similarly to the filaments of au-' dion 26, and master. audion 27, to the common source 47, auxiliary source 42, and

46, respectively, and resistance 50 and 51 respectively. The plates of the "auxiliary audions, however, are each connected to one or more electro-responsive devices in series, instead of the transformer as in the case of audion 26, or'v of the plurality of transformers, as'in the case of master audion 27.

The current sources 28, 36, 42, 46, 47, etc.,-

may be of any suitable type, but for illustrative purpose I have shown them as batteries., The resistances 48, 49, 50, 51, etc.,

may be of any variable resistance type well is transmitted. to the au'dion'26 through the step-up transf'ormer25. This audion serves to amplify the current received and trans:

mits the same by means of transformer 29 to the master audlon 27. The master audion in turn amplifies the received current, and by means of the transformers 33, 34, etc., transmits the same to the auxiliary audions 31, 32, etc, each of which am lifies the received current so that it may e utilized by their associated electro-responsive devices.

It is essential that the grids of the various audions should not be connected directly to any source of electro-motive force, while at the same time it is desirable to supply the filaments of all of the audions with current from the same source. I accomplish this by open circuiting one side of the secondaries of each of the transformers employed, as herein before described A condenser may be employed instead of the open-circuited gap as shown by dotted lines at '30 and 53, but I find that in practice I secure better results and more efficient reproducing and amplifying action by the respective audions, with oneside of the secondaries of the transformers open-circuited.

It is clear from the fore oing description that a single auxiliary audion may be employed in connection with a single or plurality of electro-responsive devices in the arrangement described. It is also obvious that a plurality of auxiliary audions may be employed, each auxiliary audion having a single or plurality of electro-responsive devices, associated therewith.

Whereas I have illustrated particular forms and arrangements for reproducing and amplifying weak pulsating currents employing a master audion and auxiliary audions, it will be understood that other arrangements may be used without departing from the scope of my invention, and consequently I am not to be limited to the arrangemen-ts shown herein.

Having now set forth the object and nature of my invention, and construction embodying the principles thereof, what I claim as new and useful and of my own invention, and desire :to secure by Letters Patent is,

1. In an amplifying device for electric currents, a source of weak pulsating currents, an amplifying device associated therewith, a plurality of amplifying devices associated with said first named amplifying device, and means to prevent interaction between said plurality of amplifying devices.

2. In an amplifying device for electric currents, a source of weak pulsating currents, a master audion associated therewith, a plurality of auxiliary audions associated with said master audion, electro-responsive devices controlled by said auxiliary audions, and, meansto prevent interaction between said auxiliary audions.

3. The combination with a source of pulsating current, an amplifying device, an electro-responsive device controlled by said amplifying device, and an-open circuited transformer intermediate said source and amplifying device.

4. The combination with a source of pulsating current, of an audion, an electro-responsive device controlled thereby, and a transformer to associate said audionwith said source, said transformer having its secondary open-circuited.

5. The combination with a source of pulsating current, of an audion, an electro-responsive device controlled by said audion, and. a transformer for associating said source and audion, the grid and filament elements of the audion, being connected to the secondary of the transformer, said secondary being open circuited.

6. Thecombination with a source of pulsating current, of an audion, a transformer having its secondary connected to the grid and filament elements of the audion, said secondary being open-circuited, and an electro-responsive device controlled by the wing element of the audion.

7. The combination with a source of pulsating current, ofa master audion, a step-up transformer connecting said master audion former associating said second master and auxiliary audions, the secondary of said last mentioned transformer being open-circuited, and an electro-responsive device controlled by said auxiliary audion.

9. The combination with audions operating as current amplifying devices and arranged in successive relation, of auxiliary audion amplifying devices arranged in parallel and associated with said first named audion amplifying devices, and electro-responsive devices controlled by said auxiliary audion amplifying devices.

10. The combination with a source of pulsating current, of an audion having its grid and filament elements in electrical connection therewith, a transformer having its primary connected to the wing element of said audion, a second audion having its grid and filament elements connected to one terminal of the secondary of said transformer, the other terminal of said secondary being open-circuited, and an electro-responsive device controlled by said second audion.

11. The combination with a source of pulsating current, of an audion having its grid element associated with said source, a plu-' ra-lity of independent auxiliary audions having their grid elements associated with the Wing element of the first named audion, and

electro-responsive devices respectively controlled by the *wing elements of said auxiliary audions.

12. Thecombination with a source of pulsating current, of an audion having its grid element associated with said source, a plurality of independent auxiliary 'au'dions,

transformersassociated with the wing ele-.

ment of said first'n'a-med audion, the. grid elements ofthe auxiliary audions being respectively associated with said transformers,

and electro-responsive devices respectively 15 LEE DE FOREST.

Witnesses:

SAMUEL-E. DARBY, Jr., MARJORIE A. GRAEVE. 

